Mack TE 64 Diff Lock Alarm

[jcutler]

I have a TE 64 Cab Over. When my driver starts the truck in the morning the diff lock alarm sounds. If you remove the cluster gauge and unplug the 4 wire harness from the cluster gauge and plug it back in the alarm stops. Also note that the diff lock is pneumatically disconnected. 

 

Any Ideas or where to start?

[The Heinz]

We see a lot of diff lock switch failures in newer Macks, but I don't know if it being pneumatically disconnected will affect that as a problem or not. I haven't seen a truck with exactly what your issue is, so I wouldn't be able to say for sure. 

[Nickdieselz]

It sounds like your TE 64 Cab Over is experiencing an electrical issue with the differential lock alarm, particularly related to the instrument cluster or its wiring. Since unplugging and replugging the 4-wire harness temporarily stops the alarm, it suggests a connection or signal issue.

Here’s where to start troubleshooting:

1. Check the Cluster Harness and Connections: Inspect the 4-wire harness going to the cluster gauge. Look for any loose, corroded, or damaged wires or connectors. Cleaning the connectors and ensuring a secure connection might solve the problem if it’s just a loose contact.

2. Inspect the Instrument Cluster Itself: The issue could be within the cluster gauge itself, as it’s possible there’s an internal fault that triggers the alarm falsely. Consider testing or replacing the cluster gauge.

3. Check for Electrical Shorts or Grounding Issues: Look for any potential shorts or grounding issues in the wiring between the diff lock system and the cluster. An intermittent ground fault could cause the alarm to trigger.

4. Pneumatic System Verification: Since the diff lock is pneumatically disconnected, ensure the pneumatic system isn’t sending any false signals or leftover pressure. Double-check any pneumatic sensors related to the diff lock to make sure they are not faulty.

5. Diagnostic Scan: If possible, hook up a diagnostic tool to check for any fault codes or signals related to the diff lock system. The alarm might be linked to an electronic control module (ECM) detecting a fault.

If you need a diagnostic tool recommendation, I would highly suggest you look in this laptop https://dieselscanners.com/products/diesel-diagnostic-laptop-scanner-tuner-truck-repair

By focusing on the wiring, connections, and the cluster gauge, you should be able to identify the root cause of this alarm issue. If the problem persists, it might be necessary to test the entire diff lock circuitry.